Choice between delayed reinforcers and fixed-ratio schedules requiring forceful responding.
This experiment measured pigeons' choices between delayed reinforcers and fixed-ratio schedules in which a force of approximately 0.48 N was needed to operate the response key. In ratio-delay conditions, subjects chose between a fixed-ratio schedule and an adjusting delay. The delay was increased or decreased several times a session in order to estimate an indifference point--a delay duration at which the two alternatives were chosen about equally often. Each ratio-delay condition was followed by a delay-delay condition in which subjects chose between the adjusting delay and a variable-time schedule, with the components of this schedule selected to match the ratio completion times of the preceding ratio-delay condition. The adjusting delays at the indifference point were longer when the alternative was a fixed-ratio schedule than when it was a matched variable-time schedule, which indicated a preference for the matched variable-time schedules over the fixed-ratio schedules. This preference increased in a nonlinear manner with increasing ratio size. This nonlinearity was inconsistent with a theory that states that indifference points for both time and ratio schedules can be predicted by multiplying the choice response-reinforcer intervals of the two types of schedules by different multiplicative constants. Two other theories, which predict nonlinear increases in preference for the matched variable-time schedules, are discussed.
Mazur
J E
JE
Psychology Department, Southern Connecticut State University, New Haven 06515.
Kralik
J D
JD
D000818:Animals; D002755:Choice Behavior; D010856:Columbidae; D003214:Conditioning, Classical; D008568:Memory; D011939:Mental Recall; D009042:Motivation; D005082:Physical Exertion; D011597:Psychomotor Performance; D012055:Reinforcement Schedule